Saturated hydrocarbon isomerization process

ABSTRACT

A process for isomerizing an isomerizable cycloparaffinic hydrocarbon by contacting the cycloparaffinic hydrocarbon with a catalyst comprising a Friedel-Crafts metal halide mixed with a higher valence halide of a metal which forms at least two metal halides.

United States Patent [191 Schmerling et al.

SATUR ATED HYDROCARBON ISOMERIZATION PROCESS Inventors: Louis Schmerling; Jerome A. Vesely,

both of Riverside, Ill.

Assignee: Universal Oil Products Company,

Des Plaines, Ill.

Filed: May 25, 1973 Appl. N0.: 364,206

Related U.S. ApplicationData Division of Se r. No. 258,133, May 30, 1972, abandoned.

US. Cl. 260/666 P, 260/666 R Int. Cl. C07c 5/28 Field of Search 260/666 R, 666 P References Cited UNITED STATES PATENTS l0/l944 McAllister et al. 260/666 R Primary Examiner-Veronica OKeefe Assistant Examiner-Veronica OKeefe Attorney, Agent, or Firm-James R. Hoatson, Jr.; Thomas K. McBride; William H. Page, II

[57] ABSTRACT A process for isomerizing an isomerizable cycloparaffinic hydrocarbon by contacting the cycloparaffinic hydrocarbon with a catalyst comprising a Friedel- Crafts metal halide mixed with a higher valence halide of a metal which forms at least two metal halides.

1 Claim, N0 Drawings SATURATED HYDROCARBON ISOMERIZATION PROCESS CROSS REFERENCE TO RELATED APPLICATIONS This application is a division of our copending and now abandoned application Ser. No. 258,133 filed on May 30, 1972, all the teachings of which are incorporated herein by specific reference thereto.

BACKGROUND OF THE INVENTION This invention relates to a process for isomerizing isomerizable saturated hydrocarbons. More specifically, this invention concerns a process for isomerizing an isomerizable alkane or cycloalkane utilizing a catalyst comprising a mixture of a Friedel-Crafts metal halide and a higher valence halide of a metal which forms at least two metal halides.

In many instances, it is desirable to convert saturated hydrocarbons from one carbon chain configuration into a different carbon chain configuration. This is particularly true in the case of certain cycloparaffinic constituents of gasoline which contribute to a higher octane number of the gasoline to a greater extent than do other cycloparaffins. Therefore, it is desirable to have cycloparaffins of a particular configuration present, and, when starting with, for example, cycloparaffms having a large number of carbon atoms in the ring structure, to have a catalyst which is capable of effecting isomerization of the cycloparaffins to provide the more desirable alkylcycloparaffins having a lesser number of carbon atoms in the ring structure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel method for isomerizing an isomerizable saturated hydrocarbon.

In an embodiment, the present invention relates to a process for isomerizing an isomerizable saturated hydrocarbon which comprises contacting said hydrocarbon with a catalyst comprising a Friedel-Crafts metal halide and a higher valence halide of a metal capable of possessing at least two valences, at isomerization conditions. and recovering the resultant isomerized hydrocarbon.

In a specific embodiment, the present invention relates to a process for isomerizing cyclooctane which comprises contacting said cyclooctane with a catalyst comprising a mixture of aluminum chloride and cupric chloride at a temperature of from about C. to about 100C. and a pressure of from about 1 atmosphere to about 100 atmospheres and recovering the resulting ethylcyclohexane.

PREFERRED EMBODlMENTS OF THE INVENTION The catalyst which is utilized to effect the isomerization of the isomerizable saturated hydrocarbons in the present invention consists of a mixture of a friedel- Crafts metal halide with a higher valence halide of a metal which is capable of existing in at least two valences. Friedel-Crafts metal halides which may be used will include in particular'aluminum chloride, aluminum bromide, Zirconium chloride, zirconium bromide and boron trifluoride. Although boron is a metalloid, for purposes of this invention it is included within the'term metal halide. Suitable metals which are capable of existing in at least two different valence states include copper, mercury, iron, tin, lead, cobalt, molybdenum, chromium, tungsten and manganese. The various bromides and chlorides of the above metal such as mercuric chloride, mercuric bromide, cupric chloride, cupric bromide, manganese perchloride, molybdenum trichloride, molybdenum tetrachloride, molybdenum pentachloride, molybdenum tribromide, molybdenum tetrabromide, molybdenum pentabromide, chromic chloride, chromic bromide, manganese perchloride, manganese perbromide, ferric chloride, ferric bromide, cobaltic chloride, cobaltic bromide, stannic chloride, stannic bromide, lead tetrachloride, etc., are thus utilizable as a component of the catalyst. The usually preferred catalysts which are utilized in the isomerization reaction comprise mixtures of aluminum chloride and cupric chloride or zirconium chloride and cupric chloride. The aluminum chloride or zirconium chloride may be used in a catalytic amount, but are preferably used in equimolar amounts with the cupric chloride, the halides being added to the reactant alkane separately or as a previously admixed complex. I

The isomerization conditions under which the reaction of the present invention is effected include a temperature of about 0C. to about 300C. and a pressure in the range from about 1 atmosphere to about 200 atmospheres or more. The particular temperature and pressure which are utilized depend upon the particular isomerizable reactant as well as the particular catalyst system employed. For example, when the isomerizable hydrocarbon is cyclooctane and the catalyst employed is a mixture of aluminum chloride and cupric chloride, a preferred temperature is in the range from about 20C. to about C. and a preferred pressure is in the range from about 1 atmosphere to about 100 atmospheres.

The isomerizable saturated hydrocarbons which may be employed in the process of the present invention include straight-chain paraffms such as n-butane, npentane, n-hexane, n-heptane, n-octane, n'-nonane, ndecane, and similar higher molecular weight normal paraffins. Also suitable for use in the present process are mildly branched-paraffins such as methylpentanes, methylhexanes, methylheptanes, etc., which may be isomerized to more branched-chain paraffins. Other suitable saturated hydrocarbons are the cycloparaffinic hydrocarbons, including, for example, cyclohexane, cycloheptane, cyclooctane, etc., and alkyl-substituted cycloparaffinic hydrocarbons, such as methylcyclohexane, methylcyclooctane, etc. Suitable saturated hy-, drocarbons also include polycyclic cycloalkanes such as, for example, decahydronaphthalene, bicyclohexyl, 61C.

The process of this invention may be effected in any suitable manner and may comprise a batch or continuous-type operation. When a batch-type operation is employed, a quantity of the isomerizable saturated hydrocarbon is sealed in an appropriate apparatus such as, for example, an autoclave of the rotating or stirred variety. In addition, the particular catalyst mixture comprising a Friedel-Crafts metal halide and a higher valence halide of a metal capable of existing in at least two valences is also placed in the autoclave. Following this, the autoclave is sealed and maintained at a predetermined operating temperature which, as noted above, may be in the range from about 0C. to about 300C. A temperature cooler than room temperature may be provided by the use of an ice bath, and elevated temperatures may be provided by conventional heating means. After completion of a predetermined residence time, which may be from about 1 minute to about 24 hours or more in duration, the autoclave is then allowed to return to room temperature, if the reaction is effected at other than room temperature. Excess pressure, if any, is discharged and the autoclave is opened. The reaction mixture is recovered and subjected to conventional means of purification, separation and recovery, said means including hydrolysis, filtration, washing, drying, distillation, etc., whereby the desired isomerized saturated hydrocarbon is separated and recovered.

It is also contemplated within the scope of this invention that the isomerization process may be effected in a continuous operation. One particular type of operation which may be employed is to continuously charge the isomerizable saturated hydrocarbon reactant to a reaction zone which contains the desired mixture of Friedel-Crafts metal halide and higher valence halide of a suitable metal. The reaction zone is maintained at a temperature and pressure similar to those described above in the batch operation. Inasmuch as the catalyst mixture is in solid form, the isomerizable alkane may be charged to the reaction zone containing the catalyst in either an upward, downward or radial flow over a fixed bed of the catalyst and thereafter the isomerized product may be continuously withdrawn, separated from the reaction zone effluent, and recovered, while any unreacted isomerizable saturated hydrocarbon may be recycled to form a portion of the feed to the reaction zone. In another continuous method of operation, moving beds of reactants and catalyst are continuously passed through the reaction zone in either co-current r countercurrent flow. In addition, another type of continuous operation which may be employed is a slurry type in which the catalyst is carried into the reaction zone in admixture with the isomerizable saturated hydrocarbon.

The following examples are given to illustrate the process of the present invention. The examples are not intended to limit the generally broad scope of the present invention in strict accordance with the embodiments thereby described.

I EXAMPLE I EXAMPLE II 8.3 grams of cyclooctane and 1 gram of cupric chloride were placed in a glass vial identical to the vial used in Example I. The vial was sealed and shaken for l minute. The vial was then allowed to stand for 20.4 hours at a temperature of 25C; The hydrocarbon in the vial was then recovered and analyzed. It was found to contain a trace of ethylcyclohexane and more than 99 per-.

cent of cyclooctane.

EXAMPLE Ill 8.3 grams of cyclooctane was placed in a glass vial identical to the vial used in Example I. 1 gram of aluminum chloride and 1 gram of cupric chloride were also introduced into the via]. The vial was sealed and shaken for 1 minute. The vial was then allowed to stand at a temperature of 25C. After standing for 5 minutes, the hydrocarbon was found to consist of 8 percent ethylcyclohexane and 92 percent cyclooctane. After 2.8 hours, the hydrocarbon in the vial consisted of 55 percent isomerized hydrocarbons. After allowing the vial to stand for 20.3 hours, the hydrocarbon was withdrawn and analyzed. It was found to be substantially completely isomerized, and was found to comprise 42 percent ethylcyclohexane and 58 percent dimethylcyclohexane. By comparing Example III with Examples I and II, it can be seen that neither of the metal halides alone resulted in significant isomerization, but when used in combination, as taught in the process of the present invention, they resulted in substantially complete isomerization.

EXAMPLE IV 8.3 grams of cyclooctane was treated with 1 gram each of aluminum chloride and chromium chloride (CrCl using the procedure described in Example III. After 96 hours at 25C., the hydrocarbon was analyzed and it was found that more than 55 percent of the cyclooctane had been isomerized. I

procedure of Example III, at least half of the cyclooctane underwent isomerization.

- EXAMPLE VI Ten cc. of n-pentane was placed in a glass vial identical to the one used in Example I. One gram each of aluminum chloride and cupric chloride were also placed in the vial. The vial was sealed and shaken, then allowed to stand for 48 hours at a temperature of 25C. The vial was then opened and the gaseous content thereof allowed to flow into a trap cooled to 78C. The condensed product was recovered. The liquid hydrocarbons in the vial were also recovered, and both the gaseous and liquid material were analyzed. The product was found to comprise 67 percent n-pentane, 24 percent isopentane, 5 percent methylpentane, 3 percent isobutane and 1 percent n-butane.

EXAMPLE VII Ten cc. of decahydronaphthalene was placed in a glass vial like the one employed in Example I. The decahydronaphthalene utilized had been analyzed previously and found to consist 50 percent of the cis-isomer and 50 percent of the trans-isomer. One gram of aluminum chloride and 1 gram of cupric chloride were also placed in the vial, which was then sealed and shaken. The vial was then allowed to stand at a temperature of 25C. for 23 hours. The contents of the vial were then removed and analyzed. The hydrocarbons were found to consist of decahydronaphthalene, of which percent was the trans-isomer and 10 percent the cisisomer.

EXAMPLE VIII VIII n-Heptane (50 grams) was stirred at room temperature with 13.5 grams each of aluminum chloride and cupric chloride for 7 hours. The mixture was then allowed to stand for 16 additional hours, after which it was analyzed by gas chromatography. It was found that over 60 percent of the n-heptane had been isomerized and cracked to lower boiling hydrocarbons.

EXAMPLE IX Two experiments were carried out with zirconium chloride using the procedures of Example I and III. In the first, 1 gram of zirconium chloride was added to 8.3 grams of cyclooctane in a vial, which was sealed and shaken for 1 minute and then warmed at 8085C. for 96 hours. The product contained only a trace of hydro- 6 carbons other than cyclooctane. In the second experiment, l gram each of zirconium chloride and cupric chloride were added to 8.3 grams of cyclooctane in an identical vial, and the mixture was treated in the same mixture of zirconium chloride and cupric chloride at a temperature of about 0C. to about 300C. and a pressure of about 1 atmosphere to about 200 atmospheres,

and recovering the resultant cyclooctane isomer. 

1. A PROCESS FOR THE ISOMERIZATION OF CYCLOOCTANE WHICH COMPRISES CONTACTING THE CYCLOOCTANE WITH A MIXTURE OF ZIRONIUM CHLORIDE AND CUPRIC CHLORIDE AT A TEMPERATURE OF ABOUT 0*C. TO ABOUT 300:C. AND A PRESSURE OF ABOUT 1 ATMOSPHERE TO ABOUT 200 ATMOSPHERES, AND RECOVERING THE RESULTANT CYCLOOCTANE ISOMER. 